Problem: The editor text field isn't available
There are extensions such as jch_optimize and also many Joomla templates contain already optimize options. In this case, you find this in your Joomla template setting. Such extensions and templates should also have options to exclude files. If the editor can't be loaded, you must exclude the ckeditor.js from the optimization.
Enter to the exclude field this path: /media/kunena/core/js/ckeditor.js
After saving, empty the cache.